Sidewall sealing pad for borehole apparatus



Oct. 3, 1967 U. E. VOETTER 3,344,860l

SIDEWALL SEALING PAD FOR BOREHOLE APPARATUS 2 Sheets-Sheet 2 l //3 /Z 22 W /g/M/ United States Patent O 3,344,860 SIDEV/ ALL SEALING PAD FOR BOREHOLE APPARATUS Ulrich E. Voetter, Houston, Tex., assignor to Schlumberger Well Surveying Corporation, Houston, Tex., a

corporation of Texas Filed May 17, 1965, Ser. No. 456,399 7 Claims. (Cl. 166-100) ABSTRACT F THE DESCLOSURE This application discloses a sealing member for use with formation testers adapted for obtaining samples of connate fluids from the walls of a borehole. More particularly, the application discloses an annular elastomeric sealing member that is mounted on a rigid tubular member. A plurality of hat plates are embedded in the sealing member to support the elastomeric material against pressure forces otherwise sufficient to dama-ge the elastomeric material during its use.

Accordingly, as will subsequently become more apparent, this invention relates to new and improved pack-olf shoes for formation fluid-sampling apparatus; and, more particularly, to sealing mem-bers ideally suited for maintaining an effective seal with the wall of a borehole while a sample of connate uid is being obtained from particularly soft earth formations.

When it is desired to obtain uid samples from particularly soft or unconsolidated earth formations, Huid-sampling apparatus such as those disclosed in either the Brieger Patent No. 2,965,176 or the Whitten Patent No. 3,261,402, are usually employed. The tool described n the Brieger patent includes an elastomeric sealing member that is selectively urged against the wall of the borehole and held there in sealing engagement to isolate a portion 0f the wall. Upon command from the surface, a movable tubular probe or so-called snorkel is then extended through an opening in the engaged sealing member and urged against the formation. By opening a selectively operable valve in the tool, a discrete volume of whatever recoverable connate uids there may be in the formation is expelled by formation pressure through the snorkel and into a low-pressure sample-receiving chamber carried on the tool. Then, after it is believed that an adequate amount of fluid sample has been obtained, a second valve in the tool is actuated to close the sample-receiving chamber and the snorkel is retracted. The tool is then retrieved to the surface of the ground where the fluid sample is examined.

The sample-taking apparatus disclosed in the Whitten patent is comprised of a combination of sample-admitting means, with each employing conventional annular sealing members. One of these sample-admitting means includes a snorkel similar to that of the Brieger patent and the other sample-admitting means employs a shaped charge to provide au entrance into a formation.

As connate fluids are expelled from a particularly soft or unconsolidated formation, formation particles, such as sand, will be continually washed away from around the forward face of the sealing member. Eventually so much of the formation face will be cut away that the sealing member will be no longer able to maintain an effective seal. In both the Brieger and Whitten apparatus, this undesirable action is minimized by progressively advancing the snorkel into the formation as particles are washed out thereby reinforcing the loose formation. It will be appreciated, however, that once the snorkel has advanced to its outer limit of travel, the continued washing away of formation particles will quickly create a large cavity that will soon extend beyond the periphery of the sealing mem- 3,344,863@ Patented Oct. 3, 1967 ICC ber. Once this occurs, the sealing member will no longer be sealed against the formation and the well control uids will be admitted through the snorkel to the sample-receiving chamber.

Another approach that has been proposed for maintaining an effective seal is to mount an annular sealing member around the forward end of a movable tubular member. Then, as more fully described in Patent No. 3,295,615 to Emmet F. Brieger and Ulrich E. Voetter, as the formation particles are washed away, the sealing member itself is progressively advanced into the cavity so created to maintain a seal around the so-called follower tube.

Although these and other measures have greatly improved the odds of obtaining fluid samples from unconsolidated formations, there are still some problems encountered in the use of such equipment. For example, the so-called follower-type packer disclosed in the aforementioned Brieger and Voetter patent may prematurely lose its seal should the formation face be non-homogeneous and the cavity develop eccentrically away from the central axis ofthe follower tube toward the periphery of the sealing member. Thus, a disproportionate amount of the elastomeric material of the sealing member will be displaced in this direction and either lose sealing contact with the formation prematurely or cause the elastomeric member to rupture. Similarly, where a shaped charge is employed as described in the Whitten patent to gain access into a formation, in some instances the entrance to the perforation will be greatly enlarged. Thus, the central portion of the sealing member is unsupported and will usually be extruded by the hydrostatic pressure of the well control uids into the somewhat frusto-conica-l perforation.

Accordingly, it is recognized by those skilled in the art that it is highly essential to the success of a fluid-sampling operation that an effective seal be maintained between the earth formation and sample-admitting means as long as possible. Moreover, as a iluid sample is being admitted through the central opening of the sealing member, the pressure on the forward face of the sealing member will be no greater than the formation pressure and usually drops to a very low value upon opening of the sample-receiving chamber. When this occurs, the differential acting across the sealing member may nearly equal the hydrostatic pressure of the well control fluids, which pressure is often substantially in excess of 10,000-p.s.i.g. Thus, to maintain an effective seal as long as possible, the sealing member must have (1) suilicient resiliency and displaceable volume to move into the cavity as it develops in the formation in front of the sealin g member, (2) Suthcient strength to withstand excessively high differential pressures, and (3) suicient toughness to withstand abrasion against the roughened walls of the borehole.

Accordingly, it is an object of the present invention to yprovide new and improved scaling members for maintaining an effective seal against the sidewall of a borehole as connate fluids are being withdrawn from adjacent soft or unconsolidated earth formations.

This and other objects of the present invention are provided by arranging resilient sealing means around a rigid central member projecting forwardly from a rigid base member and one or more rigid lateral members spaced fowardly of the base member.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention7 both as to its organization and manner of operation together with further objects and advantages thereof, may best be understood by way of illustration and example of certain embodiments when taken in conjunction with the accompanying drawings, in which:

FIG. 1 depicts sample-taking apparatus employing the sealing means of the present invention as it might appear within a borehole;

FIG. 2 is a simplified, schematic representation of the sample-taking apparatus illustrated in FIG. 1;

FIG. 3 is a cross-sectional View in elevation of a portion of the apparatus of FIG. 1 and an embodiment of a sealing member arranged in accordance with the present invention; and

FIG. 4 is a cross-sectional View in plan of the apparatus shown in FIG. 3 and illustrating a typical condition of its operation.

Turning now to FIG. l, fluid-sampling apparatus incorporating the principles of the present invention is shown suspended from a multi-conductor cable 11 in a borehole 12 containing well control iluids 13 and positioned adjacent a particular earth formation 14 for collecting a sample of connate uid therefrom. The cable 11 is spooled from a winch 15 at the earths surface, with some of its conductors being connected to a switch 16a for selective connection to a conventional power source 15b and others being connected to conventional indicating-and-recording apparatus 17. The fluid-sampling apparatus 10 is comprised of an elongated body 18, which, to facilitate manufacture and assembly, may be arranged to include tandemly connected sections. Longitudinally spaced, sample-admitting means 19 and 20 arranged in accordance with the principles of the present invention are mounted along one side of the body 18 and extendible wall-engaging means 21 are mounted on the opposite side. In the position illustratedin FIG. 1, the wall-engaging means 21 have been extended to laterally shift the huid-sampling apparatus 10 in the borehole 12 and sealingly couple the sample-admitting means 19 and 20 with the exposed face of the formation 14 in preparation for obtaining a sample of connate uids therein.

Inasmuch as the particular details of its various components are not necessary for a full understanding of the present invention, the duid-sampling apparatus 10 is shown only schematically in FIG. 2 to illustrate the overall relation of its other components to the sample-admitting means 19 and 20 and their respective sealing members 22 and 23 arranged in accordance with the present invention. Accordingly, these other components may well be those described in greater detail in the aforementioned Whitten and Brieger patents; and their descriptions will therefore be limited to only that necessary for understanding their basic operation and general relation to one another and to the present invention.

As illustrated in FIG. 2, the fluid-sampling apparatus 10 is basically comprised of a hydraulic system 24 which utilizes the hydrostatic pressure of the well control uids 13 to develop an increased hydraulic pressure for actuating the apparatus, sample-admitting means 19 and 20 employing the sealing members 22 and 23, and a samplecollecting system 25 for obtaining a sample of connate fluids.

After the apparatus 16 has been positioned adjacent the formation 14, the hydraulic system 24 is activated from the surface. The wall-engaging means 21 are extended to laterally shift the apparatus 10 and sealingly engage the sealing members 22 and 23 against the exposed face of the formation 14 for obtaining a fluid sample. Once a sample has been collected in the sample-collecting system 25, the pressure in the hydraulic system 24 is relieved to disengage the wall-engaging means 21 and sample-admitting means 19 and 20 for retrieval of the apparatus 10. Y

The hydraulic system 24 may, for example, be generally of the type described in U.S. Patent No. 3,011,554 granted to Robert Desbrandes and includes a master piston 26 slidably mounted in a stepped cylinder 27 in the body 18. An electrically actuated mud valve 28 (such as shown in FIG. 4 of the Desbrandes patent) is selectively operable to admit the well 'control uids 13 through a passage 29 into an enlarged-diameter portion 30 of the cylinder 27 above the piston 26. Thus, whenever the mud valve 28 is opened, the hydrostatic pressure of the well control fluids 13 will drive the master piston 26 inwardly to develop a somewhat greater hydraulic pressure in a reduced-diameter portion 31 of the cylinder 27 below the piston. This developed hydraulic pressure will, of course, be equal to the product of the hydrostatic pressure multiplied by the ratio of the areas of the enlarged end 32 and the reduced end 33 of the piston 26.

A pressure-regulating valve 34 (such as the one shown in FIGS. 8 and 8a of the Desbrandes patent) responds to the hydrostatic pressure of the well control fluids 13 to maintain the hydraulic pressure in an outlet conduit 35 downstream of the valve 34 at a predetermined differential above the hydrostatic pressure.

The hydraulic system 24 also includes a hydraulic fluid dump chamber 36 that is connected to a hydraulic actuator 37 of a normally-closed, pressure-equalizing valve 38 and via a normally-closed, electrically-actuated valve 39 (such as shown in FIG. 7 of theDesbrandes patent) to the main hydraulic conduit 35. Dump chamber 36 is normally at atmospheric pressure and is divided into larger and smaller compartments 4t) and 41 by a partition 42 in which an orifice 43 is mounted. When it is desired to retrieve the apparatus 10, the electrically-actuated valve 39 is opened to admit hydraulic fluid from the main conduit 35 into the smaller compartment 41 of the dump chamber 36 and, via conduit 44, to the actuator piston 37 of the pressure-equalizing valve 38. Although the hydraulic pressure in the main conduit 35 is immediately reduced somewhat when valve 39 is opened, the lower compartment 41 and orifice 43 are suitably sized to enable the hydraulic actuator 37 -to open the equalizing valve 38 before the hydraulic pressure has dropped to its nal level.

The pressure-equalizing valve 3-8 is actuated by the actuator piston 37 which has a protruding stop 45 and is slidably received within an enlarged-diameter portion 45 of a stepped cylinder 47. The reduced-diameter portion 48 of the cylinder 47 receives the slidable pressureequalizing valve 38 which has a rearwardly extending projection 49 that is normally engaged against the forward face of the actuator piston 37. In its normal position as illustrated in FIG. 2, the valve member 38 blocks fluid communication between a conduit 50l leading to the sample-admitting means 19 and 20 and a conduit 51 opening to the exterior of the apparatus 10. Thus, it will be appreciated that whenever hydraulic uid is admitted through valve 39 to the dump chamber 36, the actuator piston 37 will shift the equalizing valve 38 outwardly to open uid communication between `conduits 50 and 51.

The extendible wall-engaging means 21 on the opposite side of the body 18 from the sample-admitting means 19 and 20 are arranged to shift the apparatus 10 laterally in a borehole prior to taking fluid samples. The hydraulically actuated wall-engaging means 21 is comprised of an extendible back-up shoe 52 which is normally held in a retracted position by springs 53 against the body 18. A piston actuator 54 is slidably received within a hydraulic cylinder 55 that is connected by a conduit 56 to the main hydraulic conduit 35. Thus, whenever the mud Valve 28 is opened, the increased pressure in the main hydraulic conduit 35 will urge the piston actuator 54 outwardly to extend the back-up shoe 52 against the adjacent exposed face of the formation.

Two different types of sample-admitting means19 and 2t) have been shown in FIG. 2 to illustrate two typical embodiments of sample-admitting means that may employ sealing members arranged in accordancewith. the present invention. The sample-admitting means 19 and 20 include longitudinally spaced lateral chambers 57 and 58 within the body 18, with the chambers being open at one end and having the annular, elastomericsealing members 22 and 23 mounted outside of the body around these openings to provide central openings 59 and 6i) for admitting fluid samples into the chambers. The chambers 57 and 58 are interconnected by a conduit 61 and connected via a normally-closed, electrically-actuated valve v62 and conduit 63 to the sample-collecting system 25.

A tubular member 64 is slidably and sealingly mounted within the forward portion of the chamber 57 and projects from the open end of the chamber. The forward end of the tubular member 64 is sealingly engaged within the central opening 59 through the sealing member 22. Thinwalled closure members 65 and 66 are mounted at opposite ends of the tubular member 64 to block flow through the central opening 59 and tubular member.

A shaped charge 67 is disposed in the rear of the upper chamber 57, with a thin-walled closure member 68 being mounted in front of the shaped charge to fuidly seal it within the rearward portion of the chamber. Thus, so long as it has not been detonated, the shaped charge 67 Will be isolated from the sample-collecting system 25 and fluid can enter the apparatus body 18 only by way of sample-admitting means 20. The shaped charge 67 is connected to electrically responsive igniter means, such as a detonator cord `69 and a blasting cap 70, that are ignitable from the surface via a conductor 70a in the cable 11. Y

Sample-admitting means in the lower chamber 53 include an actuator piston 71 that is sealingly and slidably mounted in the rear of the chamber and adapted to urge a tubular pro'be 72 forwardly in the chamber and through an annular member 73 mounted within the central opening 6i) in the sealing member. This snorkel tube 72 may, for example, be generally arranged as shown in FIG. 3 of the aforementioned Whitten patent. An O-ring 74 in the annular member 73 liuidly seals the forward end of the snorkel tube 72. Thus, iiuids must enter the open forward end of the snorkel tube and enter the charnber 58 by way of a lateral port 75 in the tube.

For delaying the operation of the sample-admitting means 20 until the wall-engaging means 21 has shifted the apparatus 10 against the formation, a conduit 76 having an orifice 77 therein connects the main hydraulic conduit 35 to the enclosed space behind the actuator piston 71 at the rear of the chamber 58.

The sample-collecting system 2S includes a samplereceiving chamber 28 which has a normally-open, hydraulically-actuated, closure or seal valve 79 (such as shown in FIG. 10 of the Desbrandes patent). The seal valve 79 is comprised of an actuator piston 8G slidably disposed in a cylinder 81 and carrying a valve member 82 adapted to move into engagement with a complementary valve seat 83 at the entrance of the sample-receiving chamber 78 to block flow communication with the main iiuid conduit 63.

The seal valve 79 is normally held open but, once it has been actuated, it will be latched in a closed position. A normally-closed, electrically actuated valve S4 connects the upper portion of the cylinder 81 to the main hydraulic conduit 35. Thus, to shut off fluid ow from the main fluid conduit 63, opening of the valve 84 will admit hydraulic fluid into the cylinder 81 above piston 80 and shift the valve member 82 downwardly into sealing engagement with the valve seat 83.

The sample-receiving chamber 78 generally includes upper and lower compartments 85 and 86 separated by a partition `S7 having a flow restriction or orilice 88. A liquid cushion S9, such as water, is disposed in the upper compartment 85 and isolated from the upper portion thereof by a oating piston 90 which is sealingly engaged within the upper compartment. Since the lower compartment 86 is empty, the connate uids entering the samplereceiving chamber 78 from conduit 63 move the piston 90 downwardly at a rate regulated by the ow of water 89 through the orifice 88.

Pressure transducers 91 and 92 are provided to continuously monitor the pressure in the hydraulic system 24 and sample-collecting system 25. These transducers 91 and 92 may, for example, be of the type shown in FIG. 9 of the Desbrandes patent and are connected by electrical leads 91a and 92a to the pressure indicating-andrecording apparatus 17 (FiG. 1) at the surface of the earth. Thus, by observing the variations in these pressure measurements, a skilled operator will be advised of each step in the operating cycle of the fluid-sampling apparatus 10.

To operate thesample-taking apparatus 18 illustrated in FIGS. l and 2, the apparatus is positioned in a borehole 12 adjacent a particular formation 14 of interest. Then, by connecting the power source 16h through switch 16a to cable conductor 28a, the mud valve 28 will be opened to admit well control fluids 13 from the passage 29 into the upper portion 3th of the master cylinder 27. This lwill drive the master piston 27 downwardly and develop a substantially greater hydraulic pressure in the reduced-diameter portion 31 of the cylinder 27. The pressure-regulating valve 34 will operate to admit hydraulic uid into the main hydraulic conduit 35 and maintain the pressure therein at a substantially constant differential above the hydrostatic pressure of the well control uids 13.

Since the other normally-closed valves 39 and 84 are not yet opened, the hydraulic fluid will be admitted initially only to conduits S6 and 76 leading to the wall-engaging means 21 and the sample-admitting means 20, respectively. However, in view of the restrictive effect of the orifice `77 in conduit 76, the piston actuator 54 will operate iirst and extend the back-up shoe -52 against one face of the borehole 12 to shift the apparatus 10 laterally in the opposite direction. Once the apparatus 10 has been shifted laterally, the annular sealing members 22 and 23 will be sealingly engaged against the opposite face of the borehole 12.

Once the hydraulic pressure in the conduit 76 downstream of the orifice 77 has risen above the hydrostatic pressure, it will be realized that the actuator piston 71 will move outwardly to urge the forward end of the snorkel tube 72 against the formation 14. Thus, it will be appreciated that the orifice 77 will delay the operation of the sample-admitting means 20 until the-sealing member 22 and 23 are sealingly engaged against the exposed face of the formation 14. lt will be understood also that'by monitoring pressure transducer 91, the operator can determine when the sealing members 22 and 23 have been fully engaged.

Once the hydraulic pressure behind piston 71 has built up to a sufficient magnitude to extend the snorkel tube 72 through the central opening 6i) of the sealing member 23, the forward end thereof will be engaged against the formation 14. Should there be a recoverable and flowable connate iiuid therein and the formation 14 is unconsolidated, upon opening of the ow-line valve 62, the sampling tube 72 will be forced by the hydraulic pressure into the formation as the fluids and loose formation particles ow into the tube. Should, however, the formation 14 be so well consolidated that no particles are washed away, the tube 72 will still remain against the formation and the connat fluids will iiow into the sampling tube and on into the sample-receiving chamber 78. It should be noted that although well control fluids 13 will enter the sample-admitting means 20 before it is actuated, their total volume will be known. Thus, since this known volume of fluids 13 is so small relative to the volume of chamber 78, their negligible effect can be corrected when analyzing the uids trapped in the chamber.

It will be appreciated, of course, that whenever the flow-line valve 62 is opened, the pressure in the main fluid conduit 63 will be immediately reduced. Thus, by monitoring pressure transducer 92, a skilled operator can determine that a fluid sample has entered the samplereceiving chamber 78.

Should there be no fluid sample collected by sampleadmitting means 2t), the operator will then connect the Y enter sample-admitting means 19 and iiow into the sample-receiving chamber 7S by way of conduits 61 and 63.

Whenever pressure measurements indicate that the sample-collecting chamber 78 is most likely full, the power switch 16a is connected to cable conductor 84a to open valve 84. Opening of valve 84 will admit hydraulic uid from the main conduit to the piston actuator 30 of the seal Valve 79 and close olf the sample-receiving chamber 78.

To recover the apparatus 10, the power switch 16a is connected to conductor 39a to open valve 39 to relieve the hydraulic pressure holding the wall-engaging means 21 in position. Opening of valve 39 will admit hydraulic fluid to the lower compartment 41 of the dump chamber 36 as well as to the rear of cylinder 46 behind the piston actuator 37 of the pressure-equalizing valve 38. As previously explained, however, the hydraulic pressure in conduit 44 will decrease slowly so that the actuator 37 will be able to first shift the equalizing valve 38 outwardly from its flow-blocking position between conduits 50 and 51. Once the well control fluids 13 are admitted from conduit 51 into the sample chambers 57 and 58, the iiuid pressure across the sealing members 22 and 23 will be equalized. Finally, as the hydraulic pressure drops in the main conduit 35, the hydrostatic pressure of the well control iiuids 13 will, with the assistance of springs 53, retract the back-up shoe 52 to free the apparatus 10 and allow it to be retrieved.

Turning now to FIG. 3, a partial cross-sectional view in elevation is shown of a portion of the body 18 and sample-admitting means 19 employing a preferred embodiment of the sealing member 22 arranged in accordance with the present invention.

Sample-admitting means 19 include a tubular body member 93 that is threadedly engaged in the forward end of the lateral chamber 57 in the apparatus 10, with an enlarged-diameter forward portion 94 of the member being received within a counterbored recess 95 in the body 18 at the forward end of the chamber. A plurality of transverse passages 96 through the wall of the body member 93 provide fluid communication from its axial bore 97 to a circumferential groove 93 around the member. O-rings 99 and 100 on both sides of the circumferential groove 9S fluidly seal the body member 93 in the lateral chamber 57 and isolate the forward portion of the chamber that is in communication with the branch conduit 50 and interconnecting conduit 61 to the other sample-admitting means.

The shaped charge 67 is disposed in the rear of the lateral chamber 57, with the forward end of the shaped charge being coaxially aligned and directed toward the axial bore 97 of the body member 93. The thin-walled closure member 68 is threadedly secured at the rear of the axial bore 97 of the body member 93 and iiuidlyV sealed therein by means of an O-ring 101.

The sealing member 22 is arranged in accordance with the principles of the present invention and is comprised of a rigid support member having an enlarged-diameter base portion 102 and a generally tubular, reduced-diameter, central portion 103 projecting forwardly therefrom.V A plurality of dat, annular, disc-like members 104-106 are spaced apart and mounted around the projecting central portion 103. An elastomeric material 107 is molded around the central member 103 and spaced support plates 104-106 and bonded against the forward face 108 of the base portion 102. A plurality of rearwardly extending projections 109 from the elastomeric material 107 are provided with inwardly directed lips 110 that are received within an annular groove 111 around the periphery of the enlarged forward portion 94 of the tubular body member 93. The forward face 112 of the elastomeric material 107 in sealing member 22 is curved at least in the horizontal plane so as to generally conform to the curvature of a borehole. A laterally projecting lug 113 from the base portion 102 is received within a complementary groove in the body 18 to align the sealing member 22 properly.

Although it will be appreciated that when used with other types of sample-admitting means (such as at 20) the sealing member (such as at 23) may be. secured against the body 18, in this illustrative embodiment of typical sample-admitting means 19, the sealing member 22 travels forwardly a limited distance during the operation of the sample-admitting means.

Accordingly, to employ the sealing member 22 as a follower-type packer, the forward end of the slidable tubular lmember 64 is secured within the tubular central portion 103 and extends rearwardly therefrom into the forward portion of the axial bore 97 Vthrough the tubular body member 93. A peripheral ange 114 around the rearward end of the slidable tubular member 64 is provided to limit the extent of the forward travel of the tubular member and sealing member 22. O-rings 115 and 116 respectively mounted in the enlarged-diameter portion 94 of the tubular body member 93 and inner bore of the tubular central portion 103 iiuidly seal the slidable tubular member 64 therein.

A plurality of circular grooves 117 interconnected by radial or transverse grooves (not shown) across the forward face of the enlarged-diameter portion 94 ofthe tubular body member 93 admit well control uids 13 into the space defined thereby behind the rearward face of the enlarged-diameter base portion 102. The thin-walled closure members 65 and 66 may be arranged by closing the forward and rearward ends of the slidable tubular member 64 so as to provide a sealed chamber 118 therein until the shaped charge 67 is detonated. It will be appreciated that the chamber 118 within the slidable tubular member 64 will remain free of uid until opened by the perforating jet, Thus, not only is the penetrating jet allowed to form Without undue interference from liquids, but the central tubular portion 103 will not be swelled by explosive pressures from detonation of the shaped charge 67 that otherwise would occur should liquids be Within the slidable tubular member 64.

The support plates 104-106 are preferably spaced apart by a corresponding number of forwardly directed shoulders, such as at 119, on the periphery of the central tubular portion 103. Thus, during the molding of the elastomeric material 107, the support plates 104-106 will be correctly positioned after the elastomeric material has been molded in place.

Although it is generally preferred that these support plates 104-106 be circular, they may also be made in other shapes. For example, since the forward face 112 of the sealing member 22 is preferably curved in the horizontal plane (not shown) to t the curvature of a borehole, it will be appreciated that the plates 104-106 may be made somewhat elliptical with their length along their major axis being as shown in FIG. 3 and their length along their minor axis (perpendicular to the plane of FIG. 3) being somewhat reduced to maintain their periphery a short distance within the elastomeric material 107. Thus, by providing a slight clearance (such as at 120 and 121) in every radial direction around each of the support plates 104-106, the peripheral portions of the elastomeric material 107 will be relatively unrestrained and be capable of moving freely in any direction to ll an adjacent cavity in an earth formation.

Although the support plates 104-106 may be secured to the central tubular portion 103, for example as on shoulder 119, it is preferred that these plates remain free relative to the central portion 103. Thus, by allowing the plates 104-106 to remain free, they may move forwardly from their respective shoulders as the resilient material 107 is extruded toward an earth formation. Then, when the resilient material 107 returns to its normal position, the plate members 104-106 will be free to return to their normal position as shown in FIG. 2. Similarly, it will be realized that should pressure differentials tending to extrude the elastomeric material 107 be directed transversely to the central axis through the sealing member 22, the support plates 104-106 will be free to tilt relative to the central axis and thereby better equalize the load on the sealing member.

It will be further appreciated that although it is preferable that the elastomeric material 107 be wholly integral and bonded to most, if not all, surfaces of the support plates 104-106 and portions 102 and 103 of the support member, the hydrostatic forces normally encountered in deep boreholes will often tear the elastomeric material away from a metal surface to which it is bonded. Accordingly, it is within the scope of the present invention to mold the elastomeric material 107 in a unitary form as shown, with the support plates 104-106 being embedded therein. Then, this assembly could be snugly fitted over the central portion 103 of the support member. Similarly, the elastomeric material 107 could also be formed in individual annular sections with the support plates 104-106 being interspersed therebetween.

Accordingly, upon operation of sample-admitting means 19, it will be appreciated that after the shaped charge 67 has been detonated to puncture the closure members 65, 66 and 68, connate fluids will be admitted through the punctured forward closure member 65 and into the slidable tubular member 64. From there, the connate fluids will ow through the transverse passages 96 and conduit 61 to the main sample conduit 63 in the body 18.

As connate iiuids are produced from an unconsolidated formation, the pressure within the central opening 59 Will approach atmospheric pressure because of the sudden drop in pressure as connate fluids are first admitted into the sample-receiving chamber 78. The hydrostatic pressure of the well control iiuids 13 will act through the transverse grooves and circular grooves 117 on the forward face of the body member 93 to urge the sealing member 22 and tube 64 outwardly toward the formation. It will be realized, of course, that as the adjacent formation crumbles, the sealing member 22 will be able to travel forwardly thereinto until its forward travel is arrested by the peripheral flange 114 at the rear of the slidable tubular member 64.

Turning now to FIG. 4, a cross-sectional view is shown in plan of the sealing member 22 illustrated in FIG. 3 as connate uids are being withdrawn from the unconsolidated earth formation 14 in the direction of arrows 122. Pressure in front of the sealing member 22 will, of course, be no greater than formation pressure and will most likely be substantially less. Thus, it will be appreciated that the hydrostatic pressure of the well control fluids 13 will be acting as shown by arrows 123 and 124 against the eX- posed portions of the sealing member 22 and tend to extrude the elastomeric material 107 inwardly into the resulting cavity 125 in the formation. The support plates 104-106, however, not only serve as a bridge across the cavity 125 to support the elastomeric material 107, but will also serve to distribute the forces more evenly across the sealing member 22. Accordingly, although high differential pressures can urge the elastomeric material 107 so far forwardly into the cavity 125 that at least the forwardmost support plate 106 is beyond the forward end of the tubular central portion 103, the sealing member 22 will still be effective until the cavity has enlarged suiciently to allow well control fluids 13 to bypass the sealing member at a circumferential point.

Thus, when a sealing member formed in accordance with the principles of the present invention is employed with sample-admitting means, such as those shown at 19 and 20 in FIGS. l and 2, the sealing -member Will pro vide a more effective seal with the sidewall of the borehole than has heretofore been possible with conventional sealing members. Although the foregoing description has been specifically directed to a so-called follower-type packer such as described in the aforementioned Brieger and Voetter patent, the same principlesmay be employd with a sealing member that is fixed to the body of the huid-sampling apparatus. In this latter instance,1of course, it will be understood that the sealing member will be capable of maintaining an effective seal only so long as the resultant cavity in the earth formation has not progressed beyond the periphery of the sealing member.

Thus, it will be appreciated that the present invention has provided new and improved sealing means for use with fluid-sampling apparatus (such as Vat 10 in FIGS. 1 and 2) that is capabie of maintaining an effective pressure seal against the sidewall of a borehole traversing a relatively soft or unconsolidated earth formation. By providing rigid support members, such as plates 104-106, within the elastomeric material, the sealing member of the present invention will be well supported to withstand the excessively high pressure differentials imposed by well control fluids in a deep well as well as be better able to carry such loads in view of the better distribution of forces thereon.

While particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects; and, therefore, the aim of the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

1. A sealing pad adapted for sealing against the wall of a well bore traversing earth formations comprising: a tubular member; reinforcing means extending laterally of said tubular member and movable relative thereto; resilient sealing means around said tubular member and reinforcing means, said resilient sealing means having a forward sealing surface adapted for sealing engagement with a wall of a well bore; and means for supporting the rearward portions of said tubular member and resilient sealing means. Y

2. A sealing pad adapted for sealing against the wall of a well bore traversing earth formations comprising: a tubular member; reinforcing means including at least one plate member disposed intermediate of the ends of said tubular member and extending laterally therefrom; re silient sealing means encompassing said reinforcing means and tubular member, said resilient sealing means having a forward sealing surface adapted for sealing engagement with a wall of a well bore; and means for supporting the rearward portions Iof said tubular member and resilient sealing means.

3. A sealing pad adapted for sealing against the wall of a well bore traversing earth formations comprising: a tubular member; reinforcing means including a plurality of plate members extending laterally of said tubular member at spaced intervals intermediate of the ends of said tubular member; resilient sealing means providing a forward sealing surface adapted for sealing engagement with a wall of a Well bore, said sealing means encompassing said tubular member and extending laterally from between said plate members beyond their outer edges; and means for supporting the rearward portions of said tubular member and resilient sealing means.

4. A sealing pad adapted for sealing against the wall of a well bore traversing earth formations comprising: a rigid member having a rearward base portion and a central tubular portion projecting forwardly from said base portion; a plurality of rigid annular plate members mounted around said tubular portion at spaced intervals intermediate of the free end of said tubular portion and said base portion; and resilient sealing means extending forwardly of said base portion and providing a forward sealing surface adapted for sealing engagement with a wall of a well bore, said sealing means encompassing said tubular portion and said plate members.

5. A sealing pad adapted for sealing against the wall of a well bore traversing earth formations comprising: a rigid member having a rearward base portion and a central tubular portion projecting forwardly from said base portion and having a plurality of external shoulders at spaced intervals intermediate of the free end of said tubular portion and said base portion; a plurality of rigid annular plate members mounted around said tubular portion and disposed against said shoulders; and resilient sealing means extending forwardly of said base portion and providing a forward sealing surface adapted for sealing engagement with a wall of a well bore, said sealing means encompassing said tubular portion and said plate members.

6. For apparatus used in a well bore traversing earth formations and containing well control uids and including means for sealing-off a portion of the wall of a well bore and for passing uid between the earth formations and the interior of said apparatus, the improvement comprising: a sealing pad adapted for sealing against the wall of a well bore including; a rigid member having a rearward base portion mounted on said apparatus and a central tubular portion projecting forwardly from said base portion; a plurality of rigid annular plate members mounted around said tubular portion at spaced intervals intermediate of the free end of said tubular portion and said 30 base portion; and resilient sealing means extending forwardly of said base portion and providing a forward sealing surface adapted for sealing engagement with a portion of the wall of a well bore, said sealing means encompassing said tubular portion and said plate members.

7. For apparatus used in a well bore traversing earth formations and containing well control uids and including means for sealing-oft a portio of the wall of a'well bore and for passing fluid between the earth formations and the interior of said apparatus, the improvement com.

prising: a sealing pad adapted for sealing against the Wall of a well bore including; a rigid member having a rearward base portion mounted on said apparatus and a central tubular portion projecting forwardly from said base portion and having a plurality of external shoulders at spaced intervals intermediate of the free end of said tubulaiportion and said base portion; a plurality of rigid annular plate members mounted around said tubular portion and disposed against said shoulders; and resilient sealing means extending forwardly of said base portion and providing a forward sealing surface adapted for sealing engagement with a portion of the Wall of a well bore, said sealing means encompassing said tubular portion and said plate members.

References Cited UNITED STATES PATENTS 3,217,804 11/1965 Peter 175--4.52 X 3,295,615 1/1967 Brieger et al 175-4.52

FOREIGN PATENTS 1,121,292 4/ 1956 France.

CHARLES E. OCONNELL, Primary Examiner.

DAVID H. BROWN, Examiner,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,344,860 October 3, 1967 Ulrich E. Voetter It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading to the printed specification, lines 4and 5, "Schlumberger Well Surveying Corporation" should read Schlumberger Technology Corporaton Column 2, line 63, "fowardly" should read forwardly Column 6, line 43, "member" should read members Column l2, line 5, "portio" should read portion Signed and sealed this 23rd day of September 1969.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, JR. 

1. A SEALING PAD ADAPTED FOR SEALING AGAINST THE WALL OF A WELL BORE TRAVERSING EARTH FORMATIONS COMPRISING: A TUBULAR MEMBER; REINFORCING MEANS EXTENDING LATERALLY OF SAID TUBULAR MEMBER AND MOVABLE RELATIVE THERETO; RESILIENT SEALING MEANS AROUND SAID TUBULAR MEMBER AND REINFORCING MEANS, SAID RESILIENT SEALING MEANS HAVING A FOR- 